While troubleshooting a loss of connectivity, you notice the log entryMar 16 08:20:16 %OSPF-5-ADJCHG: Process 1. Nbr 1.1.1.130 on Vlan30 from FULL toEXSTART. SeqNumberMismatchAfter logging into the device, you notice that the router seems to be stuck in the EXSTART stateWhen does this problem most frequently occur?

during startup of the OSPF process

when there is a mismatch between MTU settings for neighbor router interfaces

Refer to the exhibit. The NOC has informed you about a problem on a Gigabit Ethernet linkbetween a newly installed CRS-1 that is running Cisco IOS XR Software and Cisco IOS router.These two routers cannot establish OSPF adjacency. When you connected to CRS-1, you noticedthat the Gigabit Ethernet interface MTU is 1500. You must adjust the interface MTU on the CiscoIOS router.Which MTU should you configure on the Cisco IOS router interface to match the MTU that isconfigured on the Cisco IOS XR software?